Embedded light wave-electromagnetic wave coupling detection head and hydraulic parameter measurement method thereof

Abstract

The application discloses an embedded light wave-electromagnetic wave coupling detection head and a hydraulic parameter measurement method thereof, and belongs to the technical field of engineering safety monitoring. The detection head is of a point type structure, comprising a packaging shell, a photosensitive sensing core and an electromagnetic excitation sensing core. The packaging shell is made of high-strength corrosion-resistant non-metallic material, and a sensing window is arranged at the front end. The photosensitive sensing core realizes stress and temperature separation detection through a series connection of double-wavelength fiber Bragg gratings. The electromagnetic excitation sensing core emits high-frequency electromagnetic waves through a micro electromagnetic coil or an interdigital electrode array. The measurement method comprises photoelectric signal synchronous acquisition, double decoupling compensation based on a temperature reference, water content and stress parameter inversion and coupling state research and judgment. The application realizes high-precision monitoring of water and force parameters at the same point, solves the problems of single parameter and high false alarm rate of traditional technologies, and is suitable for safety monitoring and hierarchical early warning of high-risk nodes of underground pipelines.

Description

Technical Field

[0001] This invention belongs to the field of engineering safety monitoring and sensing technology, specifically involving an embedded optical-electromagnetic wave coupled probe and its hydraulic parameter measurement method. Background Technology

[0002] Statistical data shows that most failures (approximately 70%-80%) in urban underground pipe networks and long-distance oil and gas pipelines occur at high-risk points such as joints, elbows, and flanges where stress is concentrated or sealing is weak. The main types of failures include media leakage, structural deformation, and cracking caused by uneven settlement.

[0003] Existing monitoring technologies have several shortcomings: traditional single-parameter sensors (such as fiber optic strain sensors and humidity sensors) can only monitor a single physical quantity and cannot reflect the coupling effect of "moisture intrusion-stress change," easily leading to false alarms or missed alarms; some composite sensors suffer from complex structures, difficult installation, and weak anti-interference capabilities, making them unsuitable for harsh environments such as underground dampness, corrosion, and electromagnetic interference; furthermore, existing measurement methods lack effective temperature compensation mechanisms, temperature drift severely affects measurement accuracy, and no coupling judgment model for water-mechanical parameters has been established, making it impossible to achieve graded early warning of faults. Therefore, there is an urgent need to develop a compact, easy-to-install, high-precision probe capable of multi-parameter coupled monitoring and a corresponding measurement method. Summary of the Invention

[0004] This invention addresses the problems existing in the prior art by providing an embedded optical-electromagnetic wave coupled detector and its hydraulic parameter measurement method, which takes into account multiple technical parameters and can improve the accuracy of pipeline monitoring and early warning.

[0005] To solve the above technical problems, the present invention provides the following technical solution: an embedded optical-electromagnetic wave coupled detector, comprising: an encapsulation shell, a photosensitive core, and an electromagnetic excitation sensing core; wherein,

[0006] The encapsulation housing is needle-shaped or rod-shaped, and a sensing window is provided at the front end of the housing;

[0007] The photosensitive core includes a special optical fiber arranged along the central axis of the packaging shell, with at least two fiber Bragg gratings of different center wavelengths engraved in series on the optical fiber: the strain grating is rigidly bonded to the packaging shell by high-temperature resistant epoxy adhesive, and the temperature grating is in a free and relaxed state or encapsulated in a quartz heat-conducting tube for transmitting temperature signals.

[0008] The electromagnetic excitation sensing core includes a miniature electromagnetic coil or interdigital electrode array disposed around the optical fiber or on the inner wall of the housing, and connected to an external excitation source via a coaxial radio frequency cable.

[0009] Furthermore, the aforementioned encapsulation shell is made of polyetheretherketone or Al2O3-based specific ceramic. The polyetheretherketone encapsulation shell is suitable for operating conditions of -40℃ to 120℃, while the Al2O3-based specific ceramic encapsulation shell is suitable for high-temperature operating conditions of -60℃ to 200℃.

[0010] Furthermore, the aforementioned rod-shaped shell has a diameter of 2-5 mm and a length of 15-30 mm, while the needle-shaped shell has a diameter of 0.8-1.5 mm and a length of 8-15 mm.

[0011] The present invention also provides a method for measuring hydraulic parameters based on the embedded optical-electromagnetic wave coupled probe, comprising the following steps:

[0012] S1. Synchronous acquisition of photoelectric signals: The probe is embedded into the preset mounting hole of the pipeline connector under test. The center wavelength signal of the fiber Bragg grating reflection is acquired by the fiber demodulator. At the same time, the complex impedance or S-parameter signal of the electromagnetic unit is acquired by the vector network analyzer or impedance analysis module to ensure that the two types of signals are synchronized in time.

[0013] S2. Dual decoupling compensation based on fiber optic temperature reference: including reading the center wavelength drift of the temperature grating to calculate the precise temperature of the current measurement point, using this temperature to correct the total wavelength drift of the strain grating to obtain the wavelength drift caused by pure mechanical stress, and combining the pre-calibrated electromagnetic module temperature response curve to perform temperature correction on the complex impedance value.

[0014] S3, Inversion calculation of water content parameter W: The real part of the equivalent dielectric constant of the medium surrounding the probe is calculated using the corrected impedance value, and then converted into volumetric water content based on the pre-established medium calibration model.

[0015] S4. Inversion calculation of local stress state: The local micro-strain is calculated by combining the wavelength drift of pure mechanical strain with the strain sensitivity coefficient of optical fiber, and then the local stress state is estimated by combining the elastic modulus of the encapsulation material and the surrounding medium.

[0016] S5. Hydraulic Coupling Status Assessment and Output: By jointly analyzing the changing trends and correlations of water content and stress, the status of the target joint is determined and corresponding early warnings are output.

[0017] In step S2, the formula for calculating the precise temperature is:

[0018] ,

[0019] in, The precise temperature at the current measuring point; This is the initial temperature corresponding to the temperature grating; This represents the center wavelength shift of the temperature grating. This is the temperature sensitivity coefficient;

[0020] The total wavelength drift of the strain grating is calculated using the following formula:

[0021] ,

[0022] in, This represents the total wavelength shift of the strain grating; This is the wavelength shift caused by purely mechanical stress. , is the temperature cross-sensitivity coefficient of the strain grating.

[0023] The wavelength shift caused by the corrected pure mechanical stress is calculated as follows:

[0024] .

[0025] Furthermore, in step S2 above, the calibration process of the electromagnetic module temperature response curve is as follows: the probe is placed in a constant temperature chamber, and within a preset time and temperature range, the complex impedance value at the corresponding temperature is measured. The temperature response function is obtained by fitting a quadratic polynomial.

[0026] ,

[0027] Where Z(T) is the complex impedance at temperature T; The complex impedance at the reference temperature; , These are the fitting coefficients;

[0028] The complex impedance value is corrected for temperature as follows:

[0029] ,

[0030] in, This is the measured complex impedance value; This is the complex impedance value at the corrected reference temperature.

[0031] Furthermore, in step S3 above, the calculation of the real part of the equivalent dielectric constant is based on the Cole-Cole model, and is calculated as follows:

[0032] ,

[0033] in, The real part of the equivalent dielectric constant of the dielectric. The center frequency of the excitation signal; For electromagnetic unit vacuum capacitor; , These are the real and imaginary parts of the corrected complex impedance, respectively.

[0034] Moisture content conversion is adopted The equation is as follows:

[0035] ,

[0036] Where W represents the volumetric water content.

[0037] Furthermore, in step S4 above, the calculation formula for local micro-strain is as follows:

[0038] ,

[0039] in, This represents the local micro-strain at the probe's location; This is the wavelength shift caused by purely mechanical stress. The strain sensitivity coefficient of the optical fiber;

[0040] The formula for calculating local stress state is:

[0041] ,

[0042] in, This is a localized stress state; It is the equivalent elastic modulus of the potting material and the surrounding medium.

[0043] Furthermore, the equivalent elastic modulus of the aforementioned potting material and the surrounding medium The calculation is performed using a mixed method, and the formula is as follows:

[0044]

[0045] in, , These are the volume fractions of the potting material and the surrounding medium, respectively. ; The elastic modulus of the potting material; It is the elastic modulus of the surrounding medium.

[0046] Furthermore, step S5 as described above includes the following steps:

[0047] S5.1 Determining the judgment threshold: First, based on historical monitoring data and material characteristics, two types of judgment thresholds are preset:

[0048] Water content change rate threshold The threshold is determined by statistically analyzing the maximum rate of change in volumetric water content of the target joint over 30 consecutive days under normal operating conditions, and taking 1.5 times the maximum rate of change as the discrimination boundary.

[0049] Stress change threshold This threshold is determined by converting the ultimate strain value corresponding to the yield deformation of the packaging shell material, and is used to determine whether the stress on the structure exceeds the safe range.

[0050] S5.2, Coupling State Judgment Rule: The system combines the water content W obtained in step S3 with the local stress state obtained in step S4 through joint analysis. Based on the real-time changing trends and their correlations, the following tiered early warnings are output:

[0051] (1) Level 1 warning, media intrusion / early leakage: If the rate of change of the measured water content W is greater than the water content change rate threshold. and local stress state If a slow, lagging upward trend subsequently appears, it is determined that there is an early medium leak at the joint, and the system outputs a level one warning signal.

[0052] (2) Level II warning, abnormal mechanical structure / uneven settlement: if the absolute value of the change in local stress state is... Greater than the stress change threshold If the water content W remains at a preset low and stable level without sudden changes, it is determined that the joint has experienced mechanical structural cracking or is affected by foundation settlement, and the system outputs a level two warning signal.

[0053] (3) Level III early warning, emergency alarm for pipe burst accident: If the measured water content W and the local stress state are consistent with the local stress state Simultaneous and drastic mutations occurred within an extremely short period of time, with each mutation exceeding [a certain threshold]. and If the system detects a major pipe burst, it will determine that a major pipe burst has occurred and output a Level 3 emergency warning.

[0054] Compared with the prior art, the beneficial technical effects of the present invention using the above technical solution are as follows:

[0055] Compared to traditional single-parameter monitoring technologies, this invention significantly improves data reliability and fault early warning accuracy, effectively solving monitoring challenges in harsh environments such as underground dampness and electromagnetic interference. Its reasonable structural design, standardized measurement process, and controllable implementation costs make it widely applicable to safety monitoring of high-risk nodes such as urban underground pipe networks, long-distance oil and gas pipelines, and tunnel segment joints, providing comprehensive technical support for safe engineering operation and possessing significant engineering application value and promising prospects for widespread adoption. For those skilled in the art, various modifications and improvements can be made without departing from the inventive concept, and these all fall within the scope of protection of this invention. Therefore, the scope of protection of this invention should be determined by the appended claims. Attached Figure Description

[0056] Figure 1 This is a schematic cross-sectional view of an embedded optical-electromagnetic wave coupled detector head structure in one embodiment;

[0057] Figure 2 This is a schematic diagram of the internal optocoupler layout of the probe in one embodiment;

[0058] Figure 3 This is a schematic diagram of the probe being deployed at a pipeline flange joint in one embodiment;

[0059] Figure 4 This is a flowchart of a water-mechanical parameter coupling measurement method in one embodiment.

[0060] The following are the labels in the diagram: 1-Encapsulation housing; 2-Fiber optic cable; 3-Electromagnetic coil; 4-Fiber Bragg grating; 5-Potting material; 6-Flange; 7-Bolt; 8-Sealing gasket; 9-Fluid channel; 10-Detector head; 11-Embedded optical-electromagnetic wave coupled detector head body. Detailed Implementation

[0061] To better understand the technical content of the present invention, specific embodiments are described below in conjunction with the accompanying drawings.

[0062] In this invention, various aspects of the invention are described with reference to the accompanying drawings, in which numerous illustrative embodiments are shown. Embodiments of the invention are not limited to those depicted in the drawings. It should be understood that the invention is implemented through any of the various concepts and embodiments described above, as well as the concepts and embodiments described in detail below, because the concepts and embodiments disclosed herein are not limited to any particular implementation. Furthermore, some aspects of the invention disclosed may be used alone or in any suitable combination with other aspects of the invention disclosed.

[0063] like Figures 1 to 3 As shown, in an exemplary embodiment, the node is a typical high-risk area of ​​stress concentration and weak sealing, the medium type is tap water, the surrounding backfill medium is silty clay, the ambient temperature range is -10℃ to 40℃, and it is fitted with a polyetheretherketone (PEEK) material encapsulation shell 1.

[0064] Preferably, in an exemplary embodiment, the embedded optical-electromagnetic wave coupling detector body 11 adopts a rod-shaped packaging structure, and the parameters of each core component are optimized and selected as follows:

[0065] The encapsulation housing 1 is made of PEEK (polyether ether ketone) material, with a diameter of 3mm and a length of 20mm. The surface anti-slip thread pitch is 1.5mm, and the front sensing window has a diameter of 2mm. It is precision machined by CNC machine tools, and the two ends of the encapsulation housing 1 are sealed by laser welding.

[0066] The photosensitive core uses a single-mode fiber 2, with two fiber Bragg gratings 4 cascaded together. The strain grating FBG1 has a center wavelength... =1535nm, center wavelength of temperature grating FBG2 =1560nm, with a wavelength spacing of 25nm, meeting the design requirement of non-overlapping wavelengths and avoiding signal interference. The strain grating FBG1 is rigidly bonded to the inner wall of the encapsulation housing 1 with high-temperature resistant epoxy adhesive, with a bonding length of 5mm, ensuring synchronous stress transmission. The temperature grating FBG2 is encapsulated in a 0.4mm thick quartz heat-conducting tube, with both ends fixed to the end of the housing, in a free and relaxed state. It only responds to temperature changes and is not affected by stress, serving as a temperature compensation reference.

[0067] The electromagnetic excitation sensing core employs a miniature electromagnetic coil structure with 80 turns, a wire diameter of 0.08 mm, and an outer diameter of 2.2 mm. It is wound onto a quartz frame and fixed to the periphery of the optical fiber. The electromagnetic coil 3 and optical fiber 2 are coaxially arranged with a spacing of 0.5 mm to ensure stable transmission and reception of electromagnetic signals. An external excitation source is connected via a 1.0 mm outer diameter coaxial RF cable. The connection between the cable and the housing is secured with a waterproof sealing joint to improve overall airtightness.

[0068] The potting material 5 fills the remaining space inside the encapsulation housing 1. Epoxy resin or silicone gel is selected to fix the optical fiber 2 and the electromagnetic coil 3, and to achieve electrical insulation and flexible sealing of the internal components.

[0069] In an exemplary embodiment, thread sealant is evenly applied to the inner wall of a pre-set mounting hole (3.2 mm in diameter and 15 mm in depth) on the flange 6. The probe 10 is then slowly inserted into the mounting hole to a depth of 2 / 3 of the shell length (i.e., 13.3 mm), and secured by tightening the surface anti-slip bolts 7. The fluid channel 9 is located inside the pipeline and is enclosed by the pipe wall and the flange 6, and is used to transport industrial media such as tap water, oil, and gas.

[0070] During installation, it is necessary to ensure that the sensing window is in direct contact with the medium on the outside of the flange gasket 8, and that the encapsulation housing 1 fits snugly against the wall of the mounting hole without any gaps, so as to avoid measurement errors caused by installation gaps.

[0071] The embodiment also provides a method for measuring hydraulic parameters using an embedded optical-electromagnetic wave coupled probe, comprising the following steps:

[0072] S1. Synchronous acquisition of photoelectric signals: The probe 10 is embedded into the preset mounting hole of the pipeline connector under test, with an embedding depth of 2 / 3 of the shell length; the center wavelength signal of the reflected fiber Bragg grating (FBG) is acquired through an optical fiber demodulator. The sampling frequency of the optical fiber demodulator is 100-1000Hz and the wavelength resolution is 0.1pm; at the same time, the complex impedance or S-parameter signal of the electromagnetic unit is acquired through a vector network analyzer or impedance analysis module to ensure that the two types of signals are synchronized in time.

[0073] S2. Dual decoupling compensation based on fiber optic temperature reference: including reading the center wavelength drift of temperature grating FBG2 to calculate the accurate temperature of the current measurement point, using this temperature to correct the total wavelength drift of strain grating FBG1 to obtain the wavelength drift caused by pure mechanical stress, and combining the pre-calibrated electromagnetic module temperature response curve to perform temperature correction on the complex impedance value.

[0074] S3, Inversion calculation of water content parameter W: The real part of the equivalent dielectric constant of the medium surrounding the probe is calculated using the corrected impedance value, and then converted into volumetric water content based on the pre-established medium calibration model.

[0075] S4, Local stress state The inversion calculation: The local micro-strain is calculated by combining the wavelength drift of pure mechanical strain with the strain sensitivity coefficient of the optical fiber, and then the local stress state is estimated by combining the elastic modulus of the encapsulation material and the surrounding medium.

[0076] S5. Hydraulic Coupling Status Assessment and Output: By jointly analyzing the changing trends and correlations of water content and stress, the status of the target joint is determined and corresponding early warnings are output.

[0077] In one exemplary embodiment, the data acquisition system consists of an optical fiber demodulation module, an electromagnetic signal acquisition module, and a synchronization control module, with the following specific configuration:

[0078] The fiber optic demodulator is a high-frequency demodulator of model SI155, with a sampling frequency set to 500Hz and a wavelength resolution of 0.1pm. It is connected to the photosensitive core of the probe head 10 through a single-mode fiber optic patch cord. The fiber optic connector adopts SC / APC type waterproof connector to ensure signal transmission stability.

[0079] The vector network analyzer selected is a portable analyzer of model E5063A, with an operating frequency band covering 1MHz~6GHz, a sweep frequency interval of 10MHz, and a measurement parameter of complex impedance. It is connected to the electromagnetic excitation sensing core through a coaxial radio frequency cable, and is suitable for the detection of media around pipelines.

[0080] The synchronization control module uses a GPS timing module to achieve time synchronization between the two types of devices, with a time synchronization error of ≤1ms. The collected data is transmitted to the background data processing system in real time via Ethernet, providing a time-unified data source for subsequent data coupling analysis.

[0081] In an exemplary embodiment, the fiber optic demodulator and vector network analyzer are started, and the acquisition duration is set to 72 consecutive hours to simultaneously acquire the reflection center wavelength signal of the fiber Bragg grating 4 and the complex impedance signal of the electromagnetic coil 3.

[0082] Specifically, the initial center wavelength of the strain grating FBG1 =1535.000nm, the initial center wavelength of the temperature grating FBG2 =1560.000nm; The vector network analyzer collects complex impedance data in the 200MHz band. The initial reference impedance Z0 = 50 + j20Ω (25℃), where j represents the real part of the resistance and the imaginary part of the reactance.

[0083] Furthermore, during the acquisition process, the timestamp is calibrated in real time through a synchronization control module to ensure that the two types of signals are fully aligned in the time dimension.

[0084] Specifically, the temperature sensitivity coefficient K of the temperature grating FBG2 is set. T =10 pm / ℃, initial temperature T0=25℃. Assume the center wavelength of the temperature grating FBG2 is collected at a certain moment. =1560.0850nm, then the wavelength shift is:

[0085] .

[0086] in, This represents the center wavelength shift of the temperature grating FBG2.

[0087] Furthermore, the precise temperature is calculated as follows:

[0088]

[0089] in, The precise temperature at the current measuring point; This represents the initial temperature corresponding to the temperature grating FBG2. This represents the center wavelength shift of the temperature grating FBG2. This is the temperature sensitivity coefficient.

[0090] In one exemplary embodiment, the temperature cross-sensitivity coefficient of the strain grating FBG1 is: = ,

[0091] The total wavelength drift of the strain grating FBG1 acquired at a certain moment is calculated as follows:

[0092] ,

[0093] in, This represents the total wavelength shift of the strain grating; This is the wavelength shift caused by purely mechanical stress. , is the temperature cross-sensitivity coefficient of the strain grating.

[0094] Furthermore, the wavelength shift caused by purely mechanical stress is corrected and calculated as follows:

[0095] .

[0096] In one exemplary embodiment, the probe 10 is placed in a constant temperature chamber and kept at a constant temperature of 5°C for 30 minutes every 5°C within the range of -20°C to 80°C. The complex impedance value at the corresponding temperature is measured, and the temperature response function is obtained by fitting a quadratic polynomial.

[0097] ,

[0098] Where Z(T) is the complex impedance at temperature T; is the complex impedance at the reference temperature (25℃); a and b are fitting coefficients, a=0.02, b=0.0005.

[0099] Furthermore, the measured complex impedance is =48+j18Ω, (T=33.5℃).

[0100] Furthermore, the complex impedance value is corrected for temperature to obtain the corrected complex impedance at the standard temperature (25℃), as shown in the following formula:

[0101] ,

[0102] in, This is the measured complex impedance value; This is the corrected complex impedance value at the reference temperature (25°C).

[0103] In one exemplary embodiment, the vacuum capacitor of the electromagnetic unit C0 = 20pF, and the center frequency of the excitation signal f0 = 200MHz (2 × 10⁻⁶). 8 The real part of the equivalent dielectric constant (Hz) is calculated based on the Cole-Cole model, as follows:

[0104] ,

[0105] in, The real part of the equivalent dielectric constant of the dielectric. The center frequency of the excitation signal (unit: Hz); For electromagnetic unit vacuum capacitor; , These are the real and imaginary parts of the corrected complex impedance, respectively.

[0106] Furthermore, adopt The equation is used to convert volumetric water content, and the specific formula is as follows:

[0107] ,

[0108] Where W represents the volumetric water content.

[0109] In an exemplary embodiment, according to the local micro-strain calculation formula: Calculate the local stress state;

[0110] in, This represents the local micro-strain at the probe's location; This is the wavelength shift caused by purely mechanical stress. The strain sensitivity coefficient of the optical fiber ranges from 1.2 to 1.5 pm / με. In this example, the value is 1.3 pm / με.

[0111] The local stress state is calculated as follows:

[0112] ,

[0113] in, This is a localized stress state; The equivalent elastic modulus of the potting material and the surrounding medium is calculated using the mixing principle, as follows:

[0114] ,

[0115] in, , These are the volume fractions of the potting material and the surrounding medium, respectively. ; The elastic modulus of the potting material (PEEK: 3.8 GPa, Al2O3 ceramic: 380 GPa). The elastic modulus of the surrounding medium (soil: 10-100MPa, steel: 206GPa).

[0116] In an exemplary embodiment, the maximum rate of change in moisture content over 30 days under normal operating conditions is statistically analyzed. By jointly analyzing the trends and correlations of moisture content and stress changes, the status of the target joint is determined and a corresponding early warning is output. This includes the following sub-steps:

[0117] S5.1 Determination of the judgment threshold

[0118] This step first presets two types of judgment thresholds based on historical monitoring data and material characteristics:

[0119] Water content change rate threshold Its unit is This threshold is determined by statistically analyzing the maximum rate of change in volumetric water content of the target joint over 30 consecutive days under normal operating conditions, and then using 1.5 times this maximum rate of change as the cutoff line.

[0120] Stress change threshold The unit is MPa. This threshold is determined by converting the ultimate strain value corresponding to the yield deformation of the packaging shell material, and is used to determine whether the structural stress exceeds the safe range.

[0121] S5.2, Coupling State Judgment Rules

[0122] The system combines the water content W obtained in step S3 with the local stress state obtained in step S4 through joint analysis. Based on the real-time changing trends and their correlations, the following tiered early warnings are output:

[0123] (1) Level 1 warning, media intrusion / early leakage: If the rate of change of the measured water content W is greater than the water content change rate threshold. and local stress state If a slow, lagging upward trend subsequently appears, it is determined that there is an early medium leak at the joint, and the system outputs a level one warning signal.

[0124] (2) Level II warning, abnormal mechanical structure / uneven settlement: if the absolute value of the measured local stress state change is... Greater than the stress change threshold And at this time, the water content W remains at a preset low and stable level (e.g. If there is no sudden change, it is determined that the joint has experienced mechanical structural cracking or is affected by foundation settlement, and the system outputs a level two early warning signal;

[0125] (3) Level III early warning, emergency alarm for pipe burst accident: If the measured water content W and the local stress state are consistent with the local stress state In a very short time (such as) Simultaneously, drastic mutations occurred, and the magnitude of each mutation exceeded [a certain threshold]. and If the system detects a major pipe burst, it will determine that a major pipe burst has occurred and output a Level 3 emergency warning.

[0126] This invention relates to an embedded optical-electromagnetic wave coupled detector head and its hydraulic parameter coupled measurement method. By coaxially integrating a photosensitive sensing core and an electromagnetically excited sensing core, it achieves high-precision, point-to-point coupled monitoring of water content and mechanical stress at high-risk nodes in underground pipelines. Specifically, the encapsulation shell uses PEEK or Al2O3-based ceramic materials, adaptable to different temperature and corrosion conditions, with a compact structure and convenient installation. A dual-wavelength fiber Bragg grating (FBG) and temperature reference "dual decoupling" compensation mechanism effectively eliminates the impact of temperature drift on measurement accuracy. Based on the Cole-Cole model and the Topp equation for water content inversion, combined with the equivalent elastic modulus stress assessment calculated using the hybrid rule, a complete hydraulic parameter coupled analysis system is constructed. Furthermore, by setting graded early warning thresholds and coupling judgment rules, accurate identification and graded response to early leaks, structural anomalies, and pipe rupture accidents are achieved.

[0127] Compared to traditional single-parameter monitoring technologies, this invention significantly improves data reliability and fault early warning accuracy, effectively solving monitoring challenges in harsh environments such as underground dampness and electromagnetic interference. Its reasonable structural design, standardized measurement process, and controllable implementation costs make it widely applicable to safety monitoring of high-risk nodes such as urban underground pipe networks, long-distance oil and gas pipelines, and tunnel segment joints, providing comprehensive technical support for safe engineering operation and possessing significant engineering application value and promising prospects for widespread adoption. For those skilled in the art, various modifications and improvements can be made without departing from the inventive concept, and these all fall within the scope of protection of this invention. Therefore, the scope of protection of this invention should be determined by the appended claims.

[0128] While the present invention has been described above with reference to preferred embodiments, it is not intended to limit the invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. An embedded optical-electromagnetic wave coupled detector head, characterized in that, include: The system comprises an encapsulation shell, a photosensitive sensing core, and an electromagnetically excited sensing core; among which... The encapsulation housing is needle-shaped or rod-shaped, and a sensing window is provided at the front end of the housing; The photosensitive core includes a special optical fiber arranged along the central axis of the packaging shell, with at least two fiber Bragg gratings of different center wavelengths engraved in series on the optical fiber: the strain grating is rigidly bonded to the packaging shell by high-temperature resistant epoxy adhesive, and the temperature grating is in a free and relaxed state or encapsulated in a quartz heat-conducting tube for transmitting temperature signals. The electromagnetic excitation sensing core includes a miniature electromagnetic coil or interdigital electrode array disposed around the optical fiber or on the inner wall of the housing, and connected to an external excitation source via a coaxial radio frequency cable.

2. The embedded optical-electromagnetic wave coupling detector head according to claim 1, characterized in that, The encapsulation shell is made of polyetheretherketone or Al2O3-based specific ceramic. The polyetheretherketone encapsulation shell is suitable for operating conditions of -40℃ to 120℃, while the Al2O3-based specific ceramic encapsulation shell is suitable for high-temperature operating conditions of -60℃ to 200℃.

3. The embedded optical-electromagnetic wave coupling detector head according to claim 1, characterized in that, The diameter of the rod-shaped shell is 2-5 mm and the length is 15-30 mm, while the diameter of the needle-shaped shell is 0.8-1.5 mm and the length is 8-15 mm.

4. A method for measuring hydraulic parameters based on the embedded optical-electromagnetic wave coupled probe according to any one of claims 1-3, characterized in that, Includes the following steps: S1. Synchronous acquisition of photoelectric signals: The probe is embedded into the preset mounting hole of the pipeline connector under test. The center wavelength signal of the fiber Bragg grating reflection is acquired by the fiber demodulator. At the same time, the complex impedance or S-parameter signal of the electromagnetic unit is acquired by the vector network analyzer or impedance analysis module to ensure that the two types of signals are synchronized in time. S2. Dual decoupling compensation based on fiber optic temperature reference: including reading the center wavelength drift of the temperature grating to calculate the precise temperature of the current measurement point, using this temperature to correct the total wavelength drift of the strain grating to obtain the wavelength drift caused by pure mechanical stress, and combining the pre-calibrated electromagnetic module temperature response curve to perform temperature correction on the complex impedance value. S3, Inversion calculation of water content parameter W: The real part of the equivalent dielectric constant of the medium surrounding the probe is calculated using the corrected impedance value, and then converted into volumetric water content based on the pre-established medium calibration model. S4. Inversion calculation of local stress state: The local micro-strain is calculated by combining the wavelength drift of pure mechanical strain with the strain sensitivity coefficient of optical fiber, and then the local stress state is estimated by combining the elastic modulus of the encapsulation material and the surrounding medium. S5. Hydraulic Coupling Status Assessment and Output: By jointly analyzing the changing trends and correlations of water content and stress, the status of the target joint is determined and corresponding early warnings are output.

5. The hydraulic parameter measurement method of the embedded optical-electromagnetic wave coupled probe according to claim 4, characterized in that, In step S2, the formula for calculating the precise temperature is: ， in, The precise temperature at the current measuring point; This is the initial temperature corresponding to the temperature grating; This represents the center wavelength shift of the temperature grating. This is the temperature sensitivity coefficient; The total wavelength drift of the strain grating is calculated using the following formula: ， in, This represents the total wavelength shift of the strain grating; This is the wavelength shift caused by purely mechanical stress. , The temperature cross-sensitivity coefficient of the strain grating; The wavelength shift caused by the corrected pure mechanical stress is calculated as follows: 。 6. The hydraulic parameter measurement method of the embedded optical-electromagnetic wave coupled probe according to claim 5, characterized in that, In step S2, the calibration process of the electromagnetic module's temperature response curve is as follows: The probe is placed in a constant temperature chamber, and within a preset time and temperature range, the complex impedance value at the corresponding temperature is measured. The temperature response function is then obtained by fitting a quadratic polynomial. ， in, The complex impedance at temperature T; The complex impedance at the reference temperature; , These are the fitting coefficients; The complex impedance value is corrected for temperature as follows: ， in, This is the measured complex impedance value; This is the complex impedance value at the corrected reference temperature.

7. The hydraulic parameter measurement method of the embedded optical-electromagnetic wave coupled probe according to claim 4, characterized in that, In step S3, the calculation of the real part of the equivalent dielectric constant is based on the Cole-Cole model, and is calculated as follows: ， in, The real part of the equivalent dielectric constant of the dielectric. The center frequency of the excitation signal; For electromagnetic unit vacuum capacitor; , These are the real and imaginary parts of the corrected complex impedance, respectively. The water content conversion uses the Topp equation, as shown below: ， Where W represents the volumetric water content.

8. The hydraulic parameter measurement method of the embedded optical-electromagnetic wave coupled probe according to claim 4, characterized in that, In step S4, the formula for calculating local micro-strain is as follows: ， in, This represents the local micro-strain at the probe's location; This is the wavelength shift caused by purely mechanical stress. The strain sensitivity coefficient of the optical fiber; The formula for calculating local stress state is: ， in, This is a localized stress state; It is the equivalent elastic modulus of the potting material and the surrounding medium.

9. The hydraulic parameter measurement method of the embedded optical-electromagnetic wave coupled probe according to claim 8, characterized in that, Equivalent elastic modulus of potting material and surrounding medium The calculation using the mixed method is as follows: , in, , These are the volume fractions of the potting material and the surrounding medium, respectively. ; The elastic modulus of the potting material; It is the elastic modulus of the surrounding medium.

10. The hydraulic parameter measurement method of the embedded optical-electromagnetic wave coupled probe according to claim 4, characterized in that, Step S5 includes the following steps: S5.1 Determination of Judgment Thresholds: First, based on historical monitoring data and material characteristics, two types of judgment thresholds are preset as follows: Water content change rate threshold The threshold The maximum rate of change in volumetric water content of the target joint under normal operating conditions over 30 consecutive days was statistically analyzed, and 1.5 times this maximum rate of change was taken as the discrimination threshold. Stress change threshold The threshold The value is determined by converting the ultimate strain value corresponding to the yield deformation of the encapsulation shell material, and is used to determine whether the structural stress exceeds the safe range. S5.2, Coupling State Judgment Rule: The system combines the water content W obtained in step S3 with the local stress state obtained in step S4 through joint analysis. Based on the real-time changing trends and their correlations, the following tiered early warnings are output: (1) Level 1 warning, media intrusion / early leakage: If the rate of change of the measured water content W is greater than the water content change rate threshold. and local stress state If a slow, lagging upward trend subsequently appears, it is determined that there is an early medium leak at the joint, and the system outputs a level one warning signal. (2) Level II warning, abnormal mechanical structure / uneven settlement: if the absolute value of the measured local stress state change is... Greater than the stress change threshold If the water content W remains at a preset low and stable level without sudden changes, it is determined that the joint has experienced mechanical structural cracking or is affected by foundation settlement, and the system outputs a level two warning signal. (3) Level III early warning, emergency alarm for pipe burst accident: If the measured water content W and the local stress state are consistent with the local stress state Simultaneous drastic mutations occur within a preset time period, and the magnitude of each mutation exceeds [a certain threshold]. and If the system detects a major pipe burst, it will determine that a major pipe burst has occurred and output a Level 3 emergency warning.

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